Resistor, inductor & capacitor

Introduction

lResistor :

A passive element which dissipates energy only.

lTwo important passive linear circuit elements:

1)Capacitor

2)Inductor

lCapacitor and inductor can store energy only and they can neither generate nor dissipate energy.

Resistor:-

l Resistance is a property of material due to which it opposes the flow of current through it.

l When electrons flow through any material, they collide with each other which gives rise to opposition to the flow of current.

lThe unit of resistor is ohm(Ω).

lIt is denoted by R.

lThe resistance of a conductor will be 1Ω

when it allows 1 A current to flow through it on

application of 1 V across its material.

lThe resistance of conducting material

is found to …be directly proportional to the

length l of the material,be inversely

proportional to the cross-sectional area of the

material.depend on the nature of material.

depend upon the temperature.

l Therefore,

R ∞ l/a

or R = ρl/a

lWhere,

R=resistance in Ω

l=length in m

a =cross section area in m²

ρ= resistivity in Ω-m

Types of resistor:-

lThere are many different Types of

Resistors available to the electronics

constructor, from very small surface mount

chip resistors up to large wirewound power

resistors.

lThey are described as below :

Carbon Composition Resistors

Carbon Film Resistors

Metal Film Resistors

Thick Film Resistors

Thin Film Resistors

Wirewound Resistors

Surface Mount Resistors

Types of resistor…

1.Carbon Composition Resistors :

lCarbon composition resistors used to be the most common type of resistors used in electronics due to their relative low cost and their great reliability.

lCarbon composition resistors use a solid block of material made from carbon powder, an insulating ceramic, and a binder material.

2. Carbon Film Resistors :

lCarbon film resistors use a thin layer of carbon on top of an insulating rod which is cut to form a narrow, long resistive path.

lBy controlling the length of the path and its width, the resistance can be precisely controlled with tolerances as tight as 1%.

3.Metal Film Resistors :

lOne of the more common axial resistor

types used today are metal film resistors.

lThey are very similar in construction to

carbon film resistors, with the main

difference being the use of a metal alloy as

the resistive material rather than carbon.

4.Thick Film Resistors :

lThey are made in a screen printing

process using a conductive ceramic

and glass mixture composite

suspended in a liquid.

lOnce the resistor has been screen

printed, it is baked at high

temperatures to remove the liquid

and fuse the ceramic and glass

composite.

5.Thin Film Resistors :

lBorrowing from semiconductor processes,

thin film resistors are made by through a

vacuum deposition process called

sputtering where a thin layer of conductive

material is deposited on an insulating

substrate.

lThis thin layer is then photo etched to

create a resistive pattern.

lBy precisely controlling the amount of

material deposited and the resistive pattern,

tolerances as tight as 0.01% can be

achieved with thin film resistors.

6. Wirewound Resistors :

lThey are made in a screen printing

process using a conductive ceramic and

glass mixture composite suspended in a

liquid.

lOnce the resistor has been screen printed,

it is baked at high temperatures to remove

the liquid and fuse the ceramic and

glass composite.

7.Surface Mount Resistors :

lSurface Mount Resistors or SMD Resistors, are very small rectangular shaped metal oxide film resistor.

lThe resistive value of the resistor is controlled by increasing the desired thickness, length or type of deposited film being used and highly accurate low tolerance resistors, down to 0.1% can be produced.

Inductor:-

lAn inductor is made of a coil of conducting wire.

l An inductor is a passive element designed to store energy in the magnetic field while a capacitor stores energy in the electric field.

Types of Inductor:-

(a) air-core.

(b) iron-core.

Capacitor:-

lA capacitor consists of two conducting plates separated by an insulator (or dielectric).

The symbol use for capacitor in the circuit diagram is ::à

lA capacitor is a two terminal circuit element that has a current through its terminals which is proportional to the derivative of the voltage across its terminals.

lThe coefficient of this proportionality is the defining characteristic of a capacitor.

lA capacitor is the device that we use to model the effect of electric fields on circuit variables.

lThe energy stored in electric fields has effects on voltage and current.

where